Field of the Invention
The present invention relates to an organic electroluminescent device (OLED) and method for fabricating the same, and more particularly, to an OLED having a touch panel.
Discussion of the Related Art
Until recently, cathode ray tubes (CRTs) have been mainly used, but in recent years, flat display devices such as plasma display panels (PDPs), liquid crystal display devices (LCDs), organic electroluminescent devices (OLEDs) or the like have been widely studied and replacing CRTs.
Among such flat panel display devices, OLEDs, which are a self-light emitting device, allow for lightweight and low profile design because a backlight unit, which is used in LCDs, is generally not required.
Furthermore, such OLEDs have advantages over LCDs in terms of excellent viewing angle and contrast ratio, advantageous power consumption, direct current (DC) low voltage driving, fast response speed, high resistance to external impacts due to solid internal structure, wide range of temperatures for use, and the like. Thus, OLEDs are widely used for portable personal devices, such as mobile terminals, PDAs, laptop computers, and the like.
In recent years, touch panels, which enables users to enter texts or pictures in a more convenient and elaborate manner, have been widely used for personal digital assistants or personal information processing devices. As a result, a touch panel type OLED, in which a touch panel is adhered to an OLED panel, has been introduced.
Such a touch panel type OLED is fabricated by forming a touch panel and an OLED panel, respectively, and then adhering the two panels to each other through an adhesive layer. The touch panel may include an upper film formed with an upper electrode, a lower film formed with a lower electrode, with a predetermined space between the upper and the lower film. The OLED panel may include a switching element, an organic light emitting diode, a protective layer for encapsulation and a protective film for protecting the OLED panel from external environments on a substrate.
Touch panels can be classified into an add-on type, an on-cell type, and an in-cell type. For a display device having the add-on type touch panel, an additional touch sensor (TS) is formed subsequent to the encapsulation process, and thus, the display panel and the touch sensor have their own separate structures that are attached together. On the other hand, for a display device having the on-cell type or in-cell type touch panel, touch sensors may be formed on both surfaces in which a display panel is encapsulated, thereby providing a structure in which the display panel and the touch sensors (TSs) are integrated.
A display device having the add-on type touch panel has high reliability because the touch contact holes are located away from the cell end line. However, a display device having the on-cell type or in-cell type touch panel may have a reliability problem because the touch contact holes are located within the display device having the touch panel.
FIG. 1 is a schematic plan view illustrating an OLED having a circular type cell region according to the related art. FIG. 2 is an enlarged plan view of portion “A” in FIG. 1, schematically illustrating a cell end line and a plurality of touch contact holes in an OLED according to the related art.
As illustrated in FIGS. 1 and 2, in case of a structure having a circular cell end line other than a linear cell end line, touch contact holes 31a, 31b, 31c are typically provided at different locations from the cell end line, with different distances, such as a first distance (d1), a second distance (d2) and a third distance (d3). This may adversely affect reliability, especially due to the touch contact hole 31a having the shorter distance (d1) from the cell end line. In other words, when touch contact holes are located on a straight line in a display device having a circular type panel, as illustrated in FIGS. 1 and 2, the touch contact holes located near the cell end line with short distances are more susceptible to moisture permeation as compared with the other touch contact holes.